JP6191582B2 - Rotation speed detector - Google Patents

Description

  The present invention relates to a rotation speed detection apparatus that outputs a signal corresponding to the rotation speed of a subject.

2. Description of the Related Art Conventionally, a rotation speed detection device that outputs a signal corresponding to the rotation speed of a rotary shaft by detecting movement of a blade provided on the rotary shaft of the turbocharger is known.
The rotation speed detection device described in Patent Document 1 processes a signal output from a sensor provided in a non-contact manner with respect to the blade, thereby rotating the rotation speed of the rotation shaft, vibration of the rotation shaft, and the blade and sensor. The clearance is detected. Among these, the number of rotations of the rotating shaft is detected by dividing the signal output from the sensor by the same dividing ratio as the number of blades and detecting the period of the divided signal.

JP 2013-224847 A

  However, in the rotation speed detection device described in Patent Document 1, the frequency division ratio for dividing the signal output from the sensor is fixed. Therefore, when the rotation speed of the rotating shaft of the turbocharger changes in a wide range from, for example, 10,000 to 300,000, the time for detecting the frequency of the divided signal changes 30 times. On the other hand, the cycle time of the control of the electronic control device that receives the signal output from the rotation speed detection device is normally set to several ms. Therefore, if an output signal with a short cycle output from the rotation speed detection device is adapted to the control cycle time of the electronic control device, the cycle output signal is updated when the rotation speed of the rotary shaft of the turbocharger is low. There is a possibility that the control response of the electronic control device cannot be followed.

  In addition, if the division ratio is set so that the output signal of a long cycle is several ms, the cycle of the signal output from the sensor will be shortened if the rotation speed of the rotating shaft of the turbocharger is increased. It is conceivable that it is difficult to accurately measure the time of the period with the frequency division ratio. Therefore, there is a concern that the accuracy of the period measurement is lowered.

The present invention has been made in view of the above problems, and transmits a signal related to the rotation speed of the subject within the control control period of the electronic control device even when the rotation speed of the subject is large. An object of the present invention is to provide a rotation speed detection device capable of performing the above.
It is another object of the present invention to provide an electronic control device that can accurately detect the number of rotations of a subject based on a signal output from the rotation number detection device.

A first invention is a rotation speed detection device that outputs a signal corresponding to the rotation speed of a subject, and includes a sensor, a comparator, a period measurement circuit, a frequency dividing variable means, and a one-shot circuit.
The sensor outputs a signal corresponding to the movement of the detected part provided in the subject. The comparator outputs a rectangular wave signal obtained by binarizing the signal output from the sensor with a predetermined threshold. The period measurement circuit measures the period of the rectangular wave signal output from the comparator. The frequency dividing means divides by a smaller dividing ratio as the period measured by the period measuring circuit is longer, or outputs without dividing, and increases as the period measured by the period measuring circuit is shorter. Divide by the ratio. The one-shot circuit has the same period as the rectangular wave signal output from the variable frequency dividing means and converts the frequency division ratio performed by the variable frequency dividing means into a signal having an identifiable waveform and outputs the signal.

Thereby, it is possible to keep the cycle of the signal output from the one-shot circuit within a predetermined time regardless of the cycle of the signal output from the sensor. Therefore, the rotation speed detection device can keep the cycle of the signal to be output within the cycle time of the control of the electronic control device that receives the signal. Therefore, even when the rotational speed range of the subject increases, the rotational speed detection device transmits a signal within the control control period of the electronic control device without increasing the load of the electronic control device, and the electronic control It is possible to update the rotational speed data of the apparatus.
In addition, since the signal output from the one-shot circuit has a waveform that can identify the division ratio performed by the frequency dividing variable means, the electronic control device that receives the signal is performed by the frequency dividing variable means according to the signal waveform. It is possible to identify the division ratio. Therefore, the electronic control unit can detect the rotation number of the subject based on the cycle of the signal output from the rotation number detection device and the frequency division ratio identified by the waveform of the signal.

The rotation speed detection device of the second invention includes a sensor, a comparator, a frequency dividing variable means, a period measuring circuit, and a communication circuit.
The sensor outputs a signal corresponding to the movement of the detected part provided in the subject. The comparator outputs a rectangular wave signal obtained by binarizing the signal output from the sensor with a predetermined threshold. The frequency dividing means divides by a smaller dividing ratio as the period of the rectangular wave signal output from the comparator becomes longer or outputs without dividing, and the period of the rectangular wave signal output from the comparator The shorter the is, the higher the division ratio. The period measuring circuit measures the period of the signal output from the variable frequency dividing means, and calculates the period count value detected by the measurement and the number corresponding to the frequency dividing ratio of the signal output from the variable frequency dividing means. Data obtained by calculating the product is output to the memory of the communication circuit. The communication circuit reads and outputs data stored in the memory.

As a result, even when the period of the rectangular wave signal output from the comparator is long, the dividing variable means divides the rectangular wave signal by a small dividing ratio, so that the period measurement period by the period measuring circuit is longer. It will never be long. Therefore, the rotation speed detection device can update data output from the communication circuit quickly.
Further, when the period of the rectangular wave signal output from the comparator is short, the variable frequency dividing means divides the rectangular wave signal by a large frequency dividing ratio, so that the accuracy of period measurement by the period measuring circuit is increased. Therefore, the rotation speed detection device can increase the accuracy of data output from the communication circuit.

A third aspect of the invention is an electronic control device that receives a communication data signal output from a communication circuit of a rotation speed detection device. The electronic control device includes a header time measurement unit, a header time comparison unit, and a period data correction unit. The header time measuring unit detects a header time included in the communication data signal. The header time comparing means compares the header time detected by the header time measuring means with the regular header time stored in the electronic control unit. The period data correction unit corrects data related to the period of the communication data signal according to the time difference between the header time detected by the header time measurement unit and the normal header time.
Thus, even when there is an error in the clock signal output from the oscillation circuit included in the rotation speed detection device, the electronic control device can correct the error in the period due to the error in the clock signal. Therefore, the electronic control unit can detect the accurate rotation number from the communication data signal output from the rotation number detection device.

It is a circuit diagram of the rotation speed detection apparatus by 1st Embodiment of this invention. It is a wave form diagram of the output signal of the rotation speed detection apparatus by 1st Embodiment. It is a table | surface which shows the relationship between LO time of the output signal of a rotation speed detection apparatus, and the frequency division ratio selected by the multiplexer. It is a time chart of the signal processing of a rotation speed detection apparatus. It is a table | surface which shows the relationship between the rotation speed of a subject, the measurement period of a sensor signal, a frequency division ratio, and the period of an output signal. 7 is a table showing a relationship between a duty ratio of an output signal and a frequency division ratio selected by a multiplexer in the rotation speed detection device according to the second embodiment of the present invention. It is a circuit diagram of the rotation speed detection apparatus by 3rd Embodiment of this invention. It is a time chart which shows the output signal of a rotation speed detection apparatus. It is a flowchart of the signal processing of a rotation speed detection apparatus. It is a flowchart of the signal processing of a rotation speed detection apparatus. It is a time chart of the signal processing of a rotation speed detection apparatus. It is a time chart of the signal processing of a rotation speed detection apparatus. It is a time chart of the signal processing of a rotation speed detection apparatus. It is a time chart of the signal processing of a rotation speed detection apparatus. It is a table | surface which shows the relationship between the rotation speed of a subject, the measurement period of a sensor signal, a frequency division ratio, and the period of an output signal. It is a circuit diagram of the rotation speed detection apparatus by 4th Embodiment of this invention. It is a time chart which shows the output signal of a rotation speed detection apparatus.

Hereinafter, a plurality of embodiments of the present invention will be described with reference to the drawings. Note that, in a plurality of embodiments, substantially the same configuration is denoted by the same reference numeral, and description thereof is omitted.
(First embodiment)
A first embodiment of the present invention is shown in FIGS. The rotational speed detection device 1 outputs a signal corresponding to the rotational speed of the rotating body by detecting the movement of the detected portion provided in the rotating body as the subject.
The rotation speed detection device 1 of the first embodiment can be used, for example, to detect the rotation speed of the rotation shaft 2 provided in the turbocharger. In this case, the rotational speed detection device 1 outputs a signal corresponding to the rotational speed of the rotary shaft 2 by detecting the movement of the blade 3 provided on the rotary shaft 2 of the turbocharger.
In the first embodiment, the rotary shaft 2 of the turbocharger corresponds to an example of the “subject” described in the claims, and the blade 3 provided on the rotary shaft 2 is the “subject” described in the claims. It corresponds to an example of “detection unit”.

First, the configuration of the rotation speed detection device 1 will be described.
The rotation speed detection device 1 includes a sensor 11, a comparator 12, a frequency dividing circuit 13, an oscillation circuit 14, a period measuring circuit 15, a frequency dividing variable means 16, a one-shot circuit 17, and the like.
The sensor 11 is, for example, a coil or the like, is provided in a non-contact manner on the blade 3 of the turbocharger serving as a detected portion, and generates an analog signal (for example, an AC signal) by the action of an eddy current generated according to the movement of the blade 3. Output. The analog signal output from the sensor 11 is input to the AC amplifier 19 via the capacitor 18 and is amplified by the AC amplifier 19.

The signal output from the AC amplifier 19 is input to the comparator 12. The comparator 12 outputs a rectangular wave signal binarized by comparing the signal output from the AC amplifier 19 with a predetermined threshold.
The rectangular wave signal output from the comparator 12 is input to the frequency divider circuit 13. The frequency dividing circuit 13 divides the rectangular wave signal output from the comparator 12 by a predetermined frequency dividing ratio.
In the present embodiment, the frequency dividing circuit 13 divides the number of blades 3 provided on the rotating shaft 2 of the turbocharger as a frequency dividing ratio. Thereby, the period of the rectangular wave signal output from the frequency dividing circuit 13 coincides with the time of one rotation of the rotating shaft 2 of the turbocharger. That is, the frequency dividing circuit 13 divides the number of detected parts (blades) provided on the subject (rotating shaft) as a frequency dividing ratio, thereby 1 of the rectangular wave signal output from the frequency dividing circuit 13. The period coincides with the time of one rotation of the rotating body.
Note that the frequency dividing circuit 13 may divide the frequency by using a number different from the number of detection units provided in the subject. Alternatively, when the cycle of the sensor 11 signal has sufficient time to perform cycle measurement, which will be described later, the rotation speed detection device 1 omits the frequency divider circuit 13 and the signal of the comparator 12 It is also possible to input the period directly to the period measurement circuit 15.

The period measuring circuit 15 measures the period of the rectangular wave output from the frequency dividing circuit 13. The period measurement by the period measurement circuit 15 is output at a predetermined interval from the oscillation circuit 14 between the rising edge of the rectangular wave signal output from the frequency dividing circuit 13 and the next rising edge or between the falling edge and the next falling edge. This is done by counting the clock signals to be transmitted.
Further, the rectangular wave signal output from the frequency dividing circuit 13 is input to the frequency dividing variable means 16. The frequency dividing means 16 includes a plurality of frequency dividers 21 to 24, a control signal generation circuit 25, a multiplexer 26, and the like.
The rectangular wave signal output from the frequency divider circuit 13 is directly input to the multiplexer 26 as a signal with a frequency division ratio of 1, and further divided by a plurality of frequency dividers 21 to 24 and then input to the multiplexer 26. .

The plurality of frequency dividers 21 to 24 sequentially divide the rectangular wave signal output from the comparator 12. That is, the first frequency divider 21 divides the rectangular wave signal output from the comparator 12 by two. The second frequency divider 22 further divides the rectangular wave signal output from the first frequency divider 21 by two. The third frequency divider 23 further divides the rectangular wave signal output from the second frequency divider 22 by two. The fourth frequency divider 24 further divides the rectangular wave signal output from the third frequency divider 23 by two. As a result, the first to fourth frequency dividers 24 divide the rectangular wave signal output from the comparator 12 with different frequency division ratios such as frequency division by 2, frequency division by 4, frequency division by 8, and frequency division by 16. Is possible.
Based on the control signal input from the control signal generation circuit 25, the multiplexer 26 is a signal directly input from the frequency divider circuit 13 to the multiplexer 26, or is output from the first to fourth frequency dividers 21 to 24. One of the signals is selected and output.

The control signal generation circuit 25 generates a control signal according to the period measured by the period measurement circuit 15. This control signal instructs the multiplexer 26 to output a signal divided by a smaller division ratio as the period measured by the period measurement circuit 15 is longer. The “small frequency division ratio” includes one. On the other hand, this control signal instructs the multiplexer 26 to output a signal divided by a larger division ratio as the period measured by the period measurement circuit 15 is shorter.
With this control signal, the signal output from the multiplexer 26 is an electronic control unit (hereinafter referred to as “ECU”) 30 that receives the output signal with the cycle of the signal output from the multiplexer 26 via the one-shot circuit 17. It is suitable for the control cycle time.

A signal output from the multiplexer 26 is input to the one-shot circuit 17. The one-shot circuit 17 outputs a pulse signal triggered by the falling edge of the rectangular wave signal output from the frequency dividing variable means 16.
In addition, a control signal indicating the frequency division ratio of the signal selected by the multiplexer 26 is input from the control signal generation circuit 25 to the one-shot circuit 17. The one-shot circuit 17 changes the LO time of the pulse signal output from the one-shot circuit 17 based on the control signal. The LO time is set based on the clock signal transmitted from the oscillation circuit 14.

FIG. 2 shows a signal output from the one-shot circuit 17. In the present embodiment, the period of the signal output from the one-shot circuit 17 is set to, for example, 3.2 ms to 6.4 ms. Note that this cycle is appropriately set so as to match the cycle time (for example, 3 ms to 8 ms) of the control of the ECU 30.
FIG. 3 shows a relationship between the frequency division ratio of the signal selected by the multiplexer 26 and the LO time of the signal output from the one-shot circuit 17. The one-shot circuit 17 changes the LO time of the signal output from the one-shot circuit 17 in accordance with the frequency division ratio of the signal selected by the multiplexer 26. As a result, the one-shot circuit 17 can identify the frequency division ratio of the rectangular wave signal output from the frequency dividing variable means 16 by the same period as that of the rectangular wave signal and performed by the frequency dividing variable means 16. It can be converted into a pulse signal having a waveform and output.

Next, signal processing by the rotation speed detection device 1 will be described.
In FIG. 4, in order from the top, the time axis, the signal directly input from the frequency divider 13 to the multiplexer 26 (divided by 1), the signal divided by the first frequency divider 21 (divided by 2), and The signal (frequency division by 4) divided by the second frequency divider 22 is shown. The lowermost stage shows an output signal output from the one-shot circuit 17. The uppermost signal (divided by 1) is also input from the frequency dividing circuit 13 to the period measuring circuit 15.
In FIG. 4, between times t0 and t1, the multiplexer 26 outputs a signal divided by two by the control signal of the control signal generation circuit 25. Therefore, the one-shot circuit 17 is also a pulse signal having the same period as that of the signal divided by two and having an LO time (for example, 0.2 ms) that can identify that the output signal is divided by two. Is output.

  Subsequently, between time t1 and time t2, the control signal generation circuit 25 determines that the period measured by the period measurement circuit 15 is shortened (* 1 in FIG. 4), and the signal from the multiplexer 26 is divided by four. The control signal is generated so as to be output. Thereafter, at time t3, the multiplexer 26 switches to a signal divided by 4 at the falling edge of the signal divided by 2 and outputs the signal. After time t3, the one-shot circuit 17 also has the same period as that of the signal divided by 4 and has an LO time (for example, 0.4 ms) that can identify that the output signal is divided by 4. Outputs a pulse signal.

  Next, between time t4 and t5, the control signal generation circuit 25 determines that the period measured by the period measurement circuit 15 has become longer (* 2 in FIG. 4), and the signal from the multiplexer 26 is divided by two. The control signal is generated so as to be output. Thereafter, at time t6, the multiplexer 26 switches to a signal divided by 2 at the falling edge of the signal divided by 4 and outputs the signal. After time t6, the one-shot circuit 17 also has the same period as that of the signal divided by two and has an LO time (for example, 0.2 ms) that can identify that the output signal is divided by two. Outputs a pulse signal.

In the table of FIG. 5, from the left column, the number of rotations of the subject, the period measured by the period measuring circuit 15, the period of the signal divided by 16, the period of the signal divided by 8, and the frequency divided by 4 The period of the signal, the period of the signal divided by two, and the period of the signal divided by one are shown. The 1-frequency signal is a signal directly input from the frequency divider circuit 13 to the multiplexer 26.
In FIG. 5, a period surrounded by a thick frame indicates a target period (3.2 ms to 6.4 ms) of a signal output from the multiplexer 26. That is, the period surrounded by the thick frame is a period of a signal output from the rotation speed detection device 1 to the ECU 30 via the one-shot circuit 17.

According to the table of FIG. 5, in this embodiment, for example, when the rotation speed of the subject is 300,000 rpm, the period measured by the period measurement circuit 15 is 0.2 ms. At this time, by using the signal divided by 16, the cycle of the signal output from the rotation speed detection device 1 becomes 3.2 ms.
For example, when the rotation speed of the subject is 0.93750,000 rpm, the period measured by the period measurement circuit 15 is 6.4 ms. At this time, by using the 1-frequency signal, the cycle of the signal output from the rotation speed detection device 1 is 6.4 ms. Therefore, when the control cycle time of the ECU 30 is, for example, 3 ms to 7 ms, the rotation speed detection device 1 can transmit a signal to the ECU 30 within the cycle time.

The rotation speed detection device 1 of the first embodiment has the following operational effects.
(1) In the first embodiment, the frequency dividing means 16 divides by a smaller dividing ratio or outputs without dividing as the period measured by the period measuring circuit 15 is longer, and the period measuring circuit. The shorter the period measured by 15, the higher the frequency division ratio. The one-shot circuit 17 converts the rectangular wave signal output from the frequency dividing variable means 16 into a signal having a waveform that can identify the frequency dividing ratio performed by the frequency dividing variable means 16 and outputs the signal.
Thereby, it is possible to keep the cycle of the signal output from the one-shot circuit 17 within a predetermined time regardless of the length of the cycle of the signal output from the sensor 11. Therefore, the rotation speed detection device 1 can keep the cycle of the output signal within the cycle time of the control of the ECU 30. Therefore, even when the height of the rotation speed of the subject increases, the rotation speed detection device 1 transmits a signal within the control cycle time of the ECU 30 without increasing the load on the ECU 30, and the rotation speed of the ECU 30 is increased. You can update the data.
Further, since the output signal of the rotation speed detection device 1 has a waveform that can identify the frequency dividing ratio performed by the frequency dividing variable means 16, the ECU 30 determines the amount that the frequency dividing variable means 16 performs according to the waveform of the output signal. It is possible to identify the circumference ratio. Therefore, the ECU 30 can detect the rotational speed of the subject based on the cycle of the output signal of the rotational speed detection device 1 and the frequency division ratio identified by the waveform of the signal.

(2) In the first embodiment, the frequency dividing variable unit 16 includes a plurality of frequency dividers 21 to 24, a control signal generation circuit 25, and a multiplexer 26.
The plurality of frequency dividers 21 to 24 divide the rectangular wave signal output from the comparator 12 at different frequency division ratios and output the result to the multiplexer 26. The multiplexer 26 selects and outputs a signal of the frequency division ratio indicated by the control signal generated by the control signal generation circuit 25 among the plurality of rectangular wave signals output from the plurality of frequency dividers 21 to 24. The control signal instructs the multiplexer 26 to output a rectangular wave signal divided by a smaller division ratio as the period measured by the period measurement circuit 15 is longer, and the period measured by the period measurement circuit 15 is larger. The multiplexer 26 is instructed to output a rectangular wave signal divided by a larger division ratio as the length is shorter. The “small frequency division ratio” includes one.
Thereby, the frequency dividing means 16 keeps the period of the rectangular wave signal output from the multiplexer 26 to the one-shot circuit 17 within a predetermined time regardless of the length of the period of the rectangular wave signal output from the comparator 12. It is possible.

(3) In the first embodiment, the one-shot circuit 17 changes the LO time of the output signal according to the frequency dividing ratio performed by the frequency dividing variable means 16.
Thereby, the rotation speed detection device 1 can simplify the circuit configuration by setting the LO time of the signal output from the one-shot circuit 17 based on the clock signal transmitted from the oscillation circuit 14.

(4) In the first embodiment, the frequency dividing circuit 13 divides the rectangular wave signal output from the comparator 12 by a predetermined frequency dividing ratio. The period measurement circuit 15 counts the clock signal output from the oscillation circuit 14 between the rising edge of the rectangular wave signal output from the frequency dividing circuit 13 and the next rising edge, or between the falling edge and the next falling edge. Thus, the period of the rectangular wave output from the frequency divider circuit 13 is measured.
Thereby, the period measuring circuit 15 measures the period of the rectangular wave signal divided by the frequency dividing circuit 13 even when the period of the rectangular wave signal output from the comparator 12 is short, so that the accuracy of the period measurement is improved. It is possible.

(Second Embodiment)
A rotation speed detection device 1 according to a second embodiment of the present invention will be described.
In the second embodiment, the one-shot circuit 17 changes the duty ratio of the output signal based on the control signal input from the control signal generation circuit 25.
FIG. 6 shows the relationship between the duty ratio of the output signal of the one-shot circuit 17 and the frequency division ratio of the signal selected by the multiplexer 26. The one-shot circuit 17 changes the duty ratio of the signal output from the one-shot circuit 17 in accordance with the frequency division ratio of the signal selected by the multiplexer 26.
In the second embodiment, it is possible to improve the identification accuracy related to the frequency division ratio in the output signal of the one-shot circuit 17 without being affected by the error of the clock signal transmitted from the oscillation circuit 14.

(Third embodiment)
A third embodiment of the present invention is shown in FIGS. The rotation speed detection device 1 of the third embodiment is applied to serial communication such as SENT (Single Edge Nibble Transmission) communication, for example.

  As shown in FIG. 7, in the third embodiment, the period measurement circuit 15 measures the period of the signal output from the multiplexer 26. The period measurement by the period measurement circuit 15 is a clock output from the oscillation circuit 14 at a predetermined interval between the rising edge of the rectangular wave signal output from the multiplexer 26 and the next rising edge, or between the falling edge and the next falling edge. This is done by counting the signals. The period measurement circuit 15 calculates the product of the “period count value” and “the number corresponding to the frequency division ratio of the signal output from the multiplexer 26”, and stores the calculated data in the memory included in the serial communication circuit 27. To store. The “number according to the frequency division ratio of the signal output from the multiplexer 26” is, for example, “the reciprocal of the frequency division ratio of the signal output from the multiplexer 26” or “the number of the signal output from the multiplexer 26”. The number obtained by multiplying the reciprocal of the frequency division ratio by N ”.

  The control signal generation circuit 25 generates a control signal according to the period measured by the period measurement circuit 15. This control signal instructs the multiplexer 26 to output a signal divided by a smaller division ratio as the period measured by the period measurement circuit 15 is longer. On the other hand, this control signal instructs the multiplexer 26 to output a signal divided by a larger division ratio as the period measured by the period measurement circuit 15 is shorter. The signal output from the multiplexer 26 is input to the period measurement circuit 15 described above.

The serial communication circuit 27 reads out data related to the period stored in the memory and outputs the data to the ECU 30 at regular communication times determined at predetermined time intervals.
The serial communication circuit 27 of the present embodiment corresponds to an example of a “communication circuit” recited in the claims.

As shown in FIG. 8, the communication data signal output from the serial communication circuit 27 to the ECU 30 is a combination of a communication adjustment header and period data. Note that the communication adjustment header time is set based on a clock signal transmitted from the oscillation circuit 14.
As shown in FIG. 7, the ECU 30 receives the output signal of the serial communication circuit 27 and detects the rotation speed of the subject. The ECU 30 includes a header time measuring unit 31, a header time comparing unit 32, and a period data correcting unit 33.

The header time measuring unit 31 detects the time of the communication adjustment header. Here, when there is an error in the clock signal of the oscillation circuit 14 included in the rotation speed detection device 1, an error occurs in the communication adjustment header time accordingly.
Next, the header time comparison unit 32 compares the time of the communication adjustment header detected by the header time measurement unit 31 with the time of the regular communication adjustment header stored in the ECU 30. Thereby, when there is an error in the clock signal of the rotation speed detection device 1, the ECU 30 can detect the magnitude of the error.

Subsequently, the cycle data correction unit 33 corrects the cycle data according to the time difference between the time of the communication adjustment header detected by the header time measurement unit 31 and the time of the regular communication adjustment header.
That is, when the time of the communication adjustment header detected by the header time measuring unit 31 is shorter than the time of the regular communication adjustment header stored in the ECU 30, the ECU 30 determines that the clock signal of the rotation speed detection device 1 is It is determined that there is an error on the earlier side, and the period data is corrected to a shorter period.
On the other hand, when the time of the communication adjustment header detected by the header time measuring unit 31 is longer than the time of the regular communication adjustment header stored in the ECU 30, the ECU 30 determines that the clock signal of the rotation speed detection device 1 is It is determined that there is an error on the slow side, and the period data is corrected to a longer period.
Thus, even when there is an error in the clock signal of the oscillation circuit 14 included in the rotation speed detection device 1, the ECU 30 can correct the error in the period due to the error and detect the accurate rotation speed.

Next, signal processing by the rotation speed detection device 1 of the third embodiment will be described with reference to the flowcharts of FIGS. 9 and 10. In FIG. 9 and FIG. 10, “step” is displayed as “S”.
This process is started by turning on the ignition switch of the vehicle.
In step 1, the control signal generation circuit 25 generates a control signal for the multiplexer 26 to select a signal divided by 1 and outputs the control signal to the multiplexer 26. As a result, the multiplexer 26 outputs the signal directly input from the frequency divider 13 to the multiplexer 26 to the period measuring circuit 15.

In step 2, the period measurement circuit 15 counts the period of the rectangular wave signal output from the multiplexer 26 with the clock signal output from the oscillation circuit 14.
In step 3, the cycle measuring circuit 15 calculates the product of the value counted in step 2 (referred to as “cycle count value”) and the “magnification” described in the map stored in the memory, and the result is serial communication. The data is stored in a memory included in the circuit 27. The “magnification” described in this map is a number obtained by multiplying the reciprocal of the frequency division ratio of the signal output from the multiplexer 26 by 16.

In step 4, the control signal generation circuit 25 determines whether or not the cycle count value counted by the cycle measurement circuit 15 in step 2 is within a predetermined range. The predetermined range is set to a regular communication time during which the serial communication circuit 27 outputs data to the ECU 30 or a time range suitable for the control cycle time of the ECU 30. In the present embodiment, the predetermined range is set from a cycle count value indicating a cycle of 3.2 ms to a cycle count value indicating a cycle of 6.4 ms.
When the cycle count value is within the predetermined range (step 4: YES), the control signal generation circuit 25 shifts the processing to step 2 without changing the frequency division ratio selected by the multiplexer 26. On the other hand, if the cycle count value is not within the predetermined range (step 4: NO), the control signal generation circuit 25 shifts the processing to step 5.

In step 5, when the cycle count value is smaller than the count value indicating the period of 3.2 ms (step 5: YES), the control signal generation circuit 25 increases the division ratio selected by the multiplexer 26 by one step. Is output to the multiplexer 26, and the process proceeds to step 2. Even if the determination in step 5 is YES, if the frequency division ratio currently selected by the multiplexer 26 is the maximum value of the frequency dividers 21 to 24 (frequency division ratio 16 in this embodiment), the control is performed. The signal generation circuit 25 shifts the processing to step 2 without changing the frequency division ratio selected by the multiplexer 26.
On the other hand, if the cycle count value is greater than or equal to the count value indicating a cycle of 3.2 ms (step 5: NO), the control signal generation circuit 25 proceeds to step 6.

In step 6, when the cycle count value is larger than the count value indicating the cycle of 6.4 ms (step 6: YES), the control signal generation circuit 25 reduces the division ratio selected by the multiplexer 26 by one step. Is output to the multiplexer 26, and the process proceeds to step 2. Even if the determination in step 6 is YES, if the division ratio currently selected by the multiplexer 26 is the minimum (division ratio 1 in this embodiment), the control signal generation circuit 25 selects the multiplexer 26. The processing is shifted to step 2 without changing the frequency dividing ratio.
Thereafter, the rotation speed detection device 1 repeatedly executes the processing from step 2 to step 8 described above.

FIG. 10 shows processing by the serial communication circuit 27.
In step 9, a signal indicating the regular communication time set at a predetermined time interval is input to the serial communication circuit 27.
Subsequently, when the signal indicating the regular communication time is input in step 10, the serial communication circuit 27 reads the data related to the cycle stored in the memory in step 3 described above, and outputs the data to the ECU 30.

Subsequently, signal processing by the rotation speed detection device 1 of the third embodiment will be described in more detail with reference to the time charts of FIGS. 11 to 14.
FIG. 11 illustrates how data is stored in the serial communication circuit 27 from the period measurement circuit 15 when the frequency division ratio of the signal output from the multiplexer 26 to the period measurement circuit 15 increases with time. is there.
In FIG. 11, in order from the top, the time axis, the signal directly input from the frequency divider 13 to the multiplexer 26 (divided by 1), the signal divided by the first frequency divider 21 (divided by 2), The signal divided by the frequency divider 22 (divided by 4), the signal divided by the third divider 23 (divided by 8), and the signal divided by the fourth divider 24 (Divide by 16) is shown.

  When a signal of 1 frequency division is input from the multiplexer 26 to the period measurement circuit 15 from time t10 to time t11, the period measurement circuit 15 counts the period count value T1 obtained by counting the period of 1 frequency division, and this signal. The corresponding multiplication factor of 16 is multiplied and the result (T1 * 16) is stored in the serial communication circuit 27.

  At time t 11, the signal output from the multiplexer 26 to the period measurement circuit 15 is switched from the signal divided by 1 to the signal divided by 2, and the signal divided by 2 is input to the period measurement circuit 15. Then, the period measuring circuit 15 multiplies the period count value T2 obtained by counting the period of the divide by 2 by 8 which is a magnification corresponding to this signal, and the result (T2 * 8) is sent to the serial communication circuit 27. Store.

  At time t <b> 13, the signal output from the multiplexer 26 to the period measurement circuit 15 is switched from the signal divided by 2 to the signal divided by 4, and the signal divided by 4 is input to the period measurement circuit 15. Then, the period measuring circuit 15 multiplies the period count value T3 obtained by counting the period of four divisions by 4 which is a magnification corresponding to this signal, and the result (T3 * 4) is sent to the serial communication circuit 27. Store.

The signal output from the multiplexer 26 to the period measuring circuit 15 at time t15 is switched from the signal divided by 4 to the signal divided by 8 and the signal divided by 8 is input to the period measuring circuit 15. Then, the cycle measuring circuit 15 multiplies the cycle count value T4 obtained by counting the divided by 8 cycle by 2 which is a magnification corresponding to this signal, and the result (T4 * 2) is sent to the serial communication circuit 27. Store.
In this way, the serial communication circuit 27 stores data related to the cycle.

FIG. 12 illustrates signal processing when the frequency division ratio of the signal output from the multiplexer 26 to the period measurement circuit 15 is increased.
In FIG. 12, the time axis, the signal directly input from the frequency divider 13 to the multiplexer 26 (divided by 1), the signal frequency-divided by the first frequency divider 21 (divided by 2), serial, from the upper stage. The data stored in the memory of the communication circuit 27 and the output signal of the serial communication circuit 27 are shown.

When a signal of 1 frequency division is input from the multiplexer 26 to the period measurement circuit 15 between time t20 and t21, the period measurement circuit 15 multiplies the period count value T21 and the magnification 16 at time t21 (T21). * 16) is stored in the serial communication circuit 27.
When the signal input from the multiplexer 26 to the period measurement circuit 15 is switched from the one-frequency-divided signal to the two-frequency-divided signal at time t21, the period measurement circuit 15 waits for the fall of the frequency-divided-by-2 signal to fall from t22 to t23. Count the period. At time t23, the period measurement circuit 15 stores the result (T22 * 8) obtained by multiplying the period count value T22 and the magnification 8 in the serial communication circuit 27.

Subsequently, the period measurement circuit 15 counts the period of the signal divided by 2 from t23 to t24, and stores the result (T23 * 8) obtained by multiplying the period count value T23 and the magnification 8 at time t24 in the serial communication circuit 27. To do.
A signal indicating the regular communication time is input to the serial communication circuit 27 at a predetermined time interval α. When a signal indicating the regular communication time is input, the serial communication circuit 27 reads and outputs the data stored in the memory.

FIG. 13 also illustrates signal processing when the frequency division ratio of the signal output from the multiplexer 26 to the period measurement circuit 15 is increased.
When a signal of 1 frequency division is input from the multiplexer 26 to the period measurement circuit 15 between time t31 and t32, the period measurement circuit 15 multiplies the period count value T31 and the magnification 16 at time t32 (T31). * 16) is stored in the serial communication circuit 27.

When the signal input from the multiplexer 26 to the period measurement circuit 15 is switched from the 1-frequency-divided signal to the 2-frequency-divided signal at time t32, the period-measurement circuit 15 waits for the fall of the 2-frequency-divided signal to t33 to t34. Count the period. At time t34, the period measurement circuit 15 stores the result (T32 * 8) obtained by multiplying the period count value T32 and the magnification 8 in the serial communication circuit 27.
When a signal indicating the regular communication time is input, the serial communication circuit 27 reads and outputs data stored in the memory.

FIG. 14 illustrates signal processing when the frequency division ratio of the signal output from the multiplexer 26 to the period measurement circuit 15 is lowered.
In FIG. 14, in order from the top, the time axis, the signal divided by the first divider 21 (divided by 2), the signal divided by the second divider 22 (divided by 4), serial The data stored in the communication circuit 27 and the output signal of the serial communication circuit 27 are shown.

When a signal divided by 4 is input from the multiplexer 26 to the period measuring circuit 15 between time t40 and t41, the period measuring circuit 15 multiplies the period count value T41 and the magnification 4 at time t41 (T41). * 4) is stored in the serial communication circuit 27.
When the signal input from the multiplexer 26 to the period measuring circuit 15 is switched from the signal divided by 4 to the signal divided by 2 at time t41, the period measuring circuit 15 waits for the falling of the signal divided by 2 to wait from t42 to t43. Count the period. At time t43, the period measurement circuit 15 stores the result (T42 * 8) obtained by multiplying the period count value T42 and the magnification 8 in the serial communication circuit 27.

Subsequently, the period measuring circuit 15 counts the period of the signal divided by two from t43 to t44, and the result (T43 * 8) obtained by multiplying the period count value T43 and the magnification 8 at time t44 is the peripheral serial communication circuit 27. To store.
When a signal indicating the regular communication time is input, the serial communication circuit 27 reads and outputs data stored in the memory.

Next, in the table of FIG. 15, from the left column, the number of rotations of the subject, the period measured by the period measurement circuit 15, the period of the signal divided by 16, the period of the signal divided by 8, 4 minutes The cycle of the signal obtained by dividing the signal, the cycle of the signal divided by two, and the cycle of the signal divided by one are shown.
In FIG. 15, a period surrounded by a thick frame indicates a target period of a signal output from the multiplexer 26.
On the other hand, in FIG. 15, the period surrounded by the alternate long and short dash line indicates a region where the period measurement circuit 15 does not count the signal period. This area is set to be twice or more of the period surrounded by the thick frame. It is conceivable that the signal in this region is temporarily output from the multiplexer 26 when the number of rotations of the subject rapidly decreases.
Note that the region indicated by the alternate long and short dash line is not limited to a region that is not less than twice the cycle surrounded by the thick frame, but can be set to a region that is an arbitrary multiple of the cycle surrounded by the thick frame. That is, when the cycle of the signal output from the multiplexer 26 becomes equal to or longer than a predetermined length with respect to the cycle of the signal output immediately before the multiplexer 26, the region of the alternate long and short dash line may be entered.

The period measuring circuit 15 does not count the period or outputs the period counter value to the serial communication circuit 27 when the signal in the region surrounded by the alternate long and short dash line is input from the multiplexer 26. Therefore, the serial communication circuit 27 maintains the data output from the period measurement circuit 15 immediately before that. Therefore, the serial communication circuit 27 outputs data related to the cycle output in the immediately preceding communication cycle time. In the meantime, the control signal generated by the control signal generation circuit 25 causes the multiplexer 26 to reduce the frequency division ratio of the signal output to the period measurement circuit 15 and to measure the period of the signal having a shorter period than the signal in the region surrounded by the one-dot chain line. Output to the circuit 15. Thereby, the period measurement circuit 15 can update the data stored in the serial communication circuit 27 in a short time. Therefore, the rotation speed detection device 1 can update data output from the serial communication circuit 27 to the ECU 30 in a short time.
Furthermore, the rotation speed detection device 1 can use the serial communication circuit 27 having a small storage capacity for storing data relating to the cycle.

The rotation speed detection device 1 of the third embodiment has the following operational effects.
(1) In the third embodiment, the variable frequency dividing means 16 divides by a smaller dividing ratio or outputs without dividing as the period of the rectangular wave output from the comparator 12 is longer, and the comparison is made. As the period of the rectangular wave signal output from the device 12 is shorter, the frequency is divided with a larger division ratio. The period measuring circuit 15 measures the period of the signal output from the multiplexer 26, and calculates the period count value detected by the measurement and the number corresponding to the frequency division ratio of the signal output from the frequency dividing variable means 16. Data obtained by calculating the product is output to the serial communication circuit 27. The serial communication circuit 27 reads out and outputs the data stored in the memory.
Thereby, when the period of the rectangular wave signal output from the comparator 12 is short, the frequency dividing means 16 divides the rectangular wave signal by a large frequency dividing ratio, so that the accuracy of the period measurement by the period measuring circuit 15 is improved. Get higher. Therefore, the rotation speed detection device 1 can improve the accuracy of data output from the serial communication circuit 27.
Further, even when the period of the rectangular wave signal output from the comparator 12 is long, the frequency dividing means 16 divides the rectangular wave signal by a small frequency dividing ratio, so that the period measurement time by the period measuring circuit 15 is long. It will not be longer than that. Therefore, the rotation speed detection device 1 can update the data output from the serial communication circuit 27 quickly.

(2) In the third embodiment, when the cycle of the signal output from the multiplexer 26 becomes equal to or longer than a predetermined length with respect to the cycle of the signal output from the multiplexer 26 immediately before, the cycle measuring circuit 15 Without measuring the signal period, the serial communication circuit 27 outputs data related to the period output in the immediately preceding communication period time.
For example, when the number of rotations of the subject suddenly decreases, it is conceivable that the cycle of the signal output from the multiplexer 26 becomes abruptly longer than the cycle of the signal output immediately before. In this case, if the period measurement circuit 15 measures the period of the signal, the data update is delayed with respect to the communication period time. For this reason, the rotation speed detection device 1 outputs the immediately preceding data from the serial communication circuit 27, measures the period of the signal appropriately divided by the frequency dividing means 16 during that time, and measures the period. The data is output from the serial communication circuit 27. The rotation speed detection device 1 can update the data output from the serial communication circuit 27 to the ECU 30 in a short time by changing the frequency division ratio during that time.
Further, the rotation speed detection device 1 can use the serial communication circuit 27 having a small storage capacity for storing data relating to the cycle.

(3) In the third embodiment, the ECU 30 includes a header time measuring unit 31, a header time comparing unit 32, and a period data correcting unit 33. The header time measuring unit 31 detects the header time included in the communication data signal. The header time comparison unit 32 compares the header time detected by the header time measurement unit 31 with the regular header time stored in the electronic control unit. The period data correction unit 33 corrects data related to the period of the communication data signal according to the time difference between the header time detected by the header time measurement unit 31 and the normal header time.
Thereby, even when there is an error in the clock signal of the oscillation circuit 14 included in the rotation speed detection device 1, the ECU 30 can correct the error in the period due to the error in the clock signal. Therefore, the ECU 30 can detect the accurate rotational speed from the communication data signal output from the rotational speed detection device 1.

(Fourth embodiment)
A fourth embodiment of the present invention is shown in FIGS.
In the fourth embodiment, in contrast to the third embodiment, the ECU 30 includes a communication cycle time measurement unit 34, a communication cycle time comparison unit 35, and a cycle data correction unit 36.
The communication cycle time measuring unit 34 measures the communication cycle time during which the communication data signal is output.
In this specification, the communication cycle time refers to the same timing in the communication format.
In the fourth embodiment, the time interval between the time when the output of one communication data signal from the rotation speed detection device 1 is started and the time when the output of the next communication data signal is started will be described as an example of the communication cycle time. However, the communication cycle time is not limited to this in the present invention. For example, the communication cycle time may be a time interval between the end timing of the communication adjustment header included in a certain communication data signal and the end timing of the communication adjustment header included in the next communication data signal. As described above, the communication cycle time refers to a time interval between various timings of one communication data signal and the next communication data signal in the communication format.

In the fourth embodiment, it is necessary for the rotation speed detection device 1 to determine this communication cycle time and to fix the communication cycle time. The rotation speed detection device 1 determines the communication cycle time based on the clock signal transmitted from the oscillation circuit 14.
The communication cycle time comparison unit 35 compares the communication cycle time measured by the communication cycle time measurement unit 34 with the regular communication cycle time stored in the ECU 30.
The cycle data correction unit 36 corrects data related to the cycle of the communication data signal according to the time difference between the communication cycle time detected by the cycle time measurement unit 34 and the regular communication cycle time.

Here, when there is an error in the clock signal of the oscillation circuit 14 included in the rotation speed detection device 1, an error occurs in the communication cycle time accordingly. Therefore, if the communication cycle time detected by the cycle time measuring unit 34 is shorter than the normal communication cycle time, the cycle data correction unit 36 has an error on the early side of the clock signal of the rotation speed detection device 1. Determine and correct the cycle data to a short cycle.
On the other hand, if the communication cycle time detected by the cycle time measurement unit 34 is longer than the normal communication cycle time, the cycle data correction unit 36 has an error on the slow side of the clock signal of the rotation speed detection device 1. Judgment is made and the cycle data is corrected to a longer cycle.

  In the fourth embodiment, the ECU 30 corrects the cycle data using the communication cycle time longer than the header time used in the third embodiment, so that the measurement accuracy is improved and the cycle of the detection pulse with higher accuracy is achieved. Data correction is possible.

(Other embodiments)
The following embodiment may be adopted with respect to the above-described embodiment.
(1) The rotational speed detection device 1 can be used for detecting the rotational speed of various rotating bodies, such as a crankshaft, in addition to a turbocharger.
(2) The rotation speed detection device 1 may process a signal output from a sensor 11 such as a Hall IC or a magnetoresistive effect element (MRE) in addition to the coil.

(3) The rotation speed detection device 1 may be configured such that the period measurement circuit 15 directly measures the period of the rectangular wave signal without dividing the rectangular wave signal output from the comparator 12 by the frequency dividing circuit 13. Good.
(4) The rotation speed detection device 1 may change the HI time of the pulse signal output from the one-shot circuit 17 in order to identify the frequency division ratio performed by the frequency division variable means 16.

(5) The rotation speed detection device 1 may include a one-shot circuit 17 that outputs a pulse signal triggered by the rise of the rectangular wave signal output from the multiplexer 26.
(6) The rotation speed detection device 1 is not limited to SENT communication, and may be configured to be applied to bidirectional communication such as LIN (Local Interconnect Network).
Thus, the present invention is not limited to the above-described embodiments, and can be implemented in various forms within the scope of the invention in addition to combining the above-described plurality of embodiments.

DESCRIPTION OF SYMBOLS 1 ... Rotation speed detection apparatus 11 ... Sensor 12 ... Comparator 15 ... Period measurement circuit 16 ... Dividing variable means 17 ... One shot circuit

Claims (8)

A rotation speed detection device (1) that outputs a signal corresponding to the rotation speed of a subject (2),
A sensor (11) for outputting a signal corresponding to the movement of the detected part (3) provided in the subject;
A comparator (12) for outputting a rectangular wave signal obtained by binarizing the signal output from the sensor with a predetermined threshold;
A period measuring circuit (15) for measuring the period of the rectangular wave signal output from the comparator;
The longer the period measured by the period measurement circuit, the smaller the division ratio is, or the output is performed without dividing, and the shorter the period measured by the period measurement circuit is, the larger the division ratio is. Frequency dividing variable means (16) for performing,
A one-shot circuit (17) for converting and outputting to a signal having the same period as the rectangular wave signal output from the frequency division variable means and having a waveform that allows the frequency division ratio performed by the frequency division variable means to be identified. And a rotation speed detection device. The frequency dividing variable means is:
A plurality of frequency dividers (21 to 24) that divide the rectangular wave signal output from the comparator by different frequency division ratios;
A control signal generation circuit (25) for generating a control signal indicating a frequency division ratio according to the period measured by the period measurement circuit;
A multiplexer (26) that selects and outputs a rectangular wave signal having a frequency division ratio indicated by the control signal among a plurality of rectangular wave signals output from the plurality of frequency dividers;
The control signal instructs the multiplexer to output a rectangular wave signal divided by a smaller division ratio as the period measured by the period measurement circuit is longer, and the period measured by the period measurement circuit is 2. The rotation speed detection apparatus according to claim 1, wherein the multiplexer is instructed to output a rectangular wave signal divided by a larger division ratio as the length becomes shorter.   3. The rotation speed detection device according to claim 1, wherein the one-shot circuit changes a signal HI or LO time according to a frequency dividing ratio performed by the frequency dividing variable unit.   3. The rotation speed detection device according to claim 1, wherein the one-shot circuit changes a duty ratio of a signal according to a frequency dividing ratio performed by the frequency dividing variable unit. A rotation speed detection device that outputs a signal corresponding to the rotation speed of a subject,
A sensor that outputs a signal corresponding to the movement of the detected portion provided in the subject;
A comparator that outputs a rectangular wave signal obtained by binarizing the signal output from the sensor with a predetermined threshold;
The longer the period of the rectangular wave signal output from the comparator is, the lower the division ratio is, or the lower frequency is output without dividing, and the shorter the period of the rectangular wave signal output from the comparator is, the larger the period is. A variable frequency dividing means for dividing the frequency by a frequency ratio;
Measures the period of the signal output from the frequency division variable means, and calculates the product of the period count value detected by the measurement and the number corresponding to the frequency division ratio of the signal output from the frequency division variable means A period measurement circuit that outputs the measured data,
A rotation speed detection device comprising: a communication circuit (27) for storing data output from the period measurement circuit and reading and outputting the data at predetermined time intervals.   When the period of the signal output from the frequency division variable means becomes equal to or longer than a predetermined length with respect to the period of the signal output from the frequency division variable means immediately before, the period measurement circuit is configured to change the frequency division. 6. The rotation speed detection apparatus according to claim 5, wherein the communication circuit outputs data relating to the cycle output in the immediately preceding communication cycle without measuring the cycle of the signal output from the means. An electronic control device (30) for receiving a communication data signal output from the communication circuit of the rotation speed detection device according to claim 5 or 6,
Header time measuring means (31) for detecting a header time of the communication data signal;
Header time comparing means (32) for comparing the header time detected by the header time measuring means with the regular header time stored in the electronic control unit;
An electronic control device comprising period data correction means (33) for correcting data relating to the period of the communication data signal in accordance with a time difference between the header time detected by the header time measurement means and a normal header time. . An electronic control device (30) for receiving a communication data signal output from the communication circuit of the rotation speed detection device according to claim 5 or 6,
Communication cycle time measuring means (34) for measuring a communication cycle time at which the communication data signal is output;
Communication cycle time comparing means (35) for comparing the communication cycle time measured by the communication cycle time measuring means with the regular communication cycle time stored in the electronic control unit;
A cycle data correction unit (36) for correcting data relating to a cycle of the communication data signal according to a time difference between the communication cycle time detected by the cycle time measuring unit and a normal communication cycle time; Control device.

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